Methods and tools for femoral resection in primary knee surgery

ABSTRACT

Femoral resection tools of the present invention include a posterior condyle alignment guide, an IM rod with an adjustable valgus bushing assembly, left and right external rotation plates, an anterior sizing boom having a stylus and a pair of medial/lateral drill guide assemblies (in one embodiment of the invention the drill guide assemblies are the combination of medial/lateral extension arms and attached (detachable) proximal positioning fixtures; in another embodiment, the proximal positioning fixtures are not part of the drill guide assembly per se), a plurality of self-tapping screws, proximal positioning fixtures (apart from any positioning fixtures that may be integrated into a drill guide assembly), and different size cutting guide blocks, each adapted to fit over the proximal positioning fixtures. According to the methods of the invention, the valgus bushing is attached to the appropriate external rotation guide plate and both are attached to the posterior alignment guide. The IM rod is inserted through the valgus bushing and in the IM canal so that the assembly rests against the distal and posterior surfaces of the femur. The stylus of the sizing boom is moved over the anterior femur and a size is indicated by indicia on a vertical post of the sizing boom. The medial/lateral drill guides are moved against the medial and lateral sides of the femur and two fixation pins (self-tapping screws) are inserted through the holes in each drill guide. The drill guide assembly, sizing boom, and alignment assembly are all removed leaving only the proximal positioning fixtures and four fixation pins. Another pair of proximal positioning fixtures may be selected; and if so are slid onto the fixation pins. A cutting block is slid onto the proximal positioning fixtures. Fixation pins are used to secure the cutting block. With the cutting block in place, five resections can be performed.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to methods and tools used in knee arthroplasty. More particularly, the invention relates to methods and tools used in total knee surgery (primary and revision applications) where an artificial femoral component is installed.

[0003] 2. Brief Description of the Prior Art

[0004] Total knee arthroplasty involves the replacement of portions of the patella, femur and tibia with artificial components. In particular, a proximal portion of the tibia and a distal portion of the femur are cut away (resected) and replaced with artificial components. As used herein, when referring to bones or other body parts, the term “proximal” means closest to the heart and the term “distal” means more distant from the heart. When referring to tools and instruments, the term “proximal” means closest to the practitioner and the term “distal” means distant from the practitioner.

[0005] There are several types of knee prostheses known in the art. One type is sometimes referred to as a “resurfacing type”. In these prostheses, the articular surface of the distal femur and proximal tibia are “resurfaced” and replaced with respective metal and plastic condylar-type articular bearing components.

[0006] The femoral component is a metallic alloy construction (cobalt-chrome alloy or 6A14V titanium alloy) and provides medial and lateral condylar bearing surfaces of multi-radius design of similar shape and geometry as the natural distal femur or femoral-side of the knee joint.

[0007] Prior art FIG. 1 is a sectional view of a state of the art femoral component. The interior of the component has five planar fixation surfaces 1-5 and an intramedullary stem 6. Prior to installation of the component, the distal femur must be prepared so that it has five fixation surfaces which closely match the interior surfaces of the component and in scenarios where additional stability is desired the IM canal is reamed to accept the IM stem of the component.

[0008] More particularly, the distal femur must be resected to have a distal cut surface (corresponding to surface 1 in FIG. 1), a posterior cut surface (corresponding to surface 2 in FIG. 1), an anterior cut surface (corresponding to surface 3 in FIG. 1), an anterior chamfer cut surface (corresponding to surface 4 in FIG. 1) and a posterior chamfer cut surface (corresponding to surface 5 in FIG. 1). These cuts are typically made with oscillating saw blades.

[0009] A number of different devices can be used to control the positioning of the saw blades. Flat metallic blocks on which the saw blade is rested, obviously rely to some extent on the skill of the surgeon to avoid tilting of the saw blade, as may happen when the saw encounters a localized harder (sclerotic) section of bone, or when the saw blade has a long travel beyond the guide surface. Slots having small clearance relative to the thickness of the saw blade may also be used. In general these offer better control of the saw blade than open style blocks.

[0010] Block type cutting guides are shown in U.S. Pat. Nos. 4,474,177, 4,487,203, 4,502,483, 4,524,766 and 4,567,885.

[0011] Fulcrum type cutting guides are described in U.S. Pat. No. 4,718,413 and also in U.S. Pat. No. 4,892,093. These consist of an upper and a lower guide surface which are linearly separated along the plane of intended cut by the saw blade. By providing a separation between the two surfaces the saw blade, including its tooth set, may be introduced between the two surfaces and then biased against them to control the cutting plane.

[0012] The separation of the guide surfaces normal to the plane of operation of the saw blade is typically matched to the thickness of the saw blade. The choice of orientation of the guide surfaces is chosen so that any deviation by the surgeon in maintenance of the contact between the saw blades and either of the guide surfaces results in conservative removal of bone, which may be subsequently corrected. The guide of U.S. Pat. No. 4,892,093 sits on the already prepared distal femur and provides for the cutting of four additional cuts.

[0013] The femoral components may be located with six degrees of freedom relative to the patient's femoral geometry. These can be expressed in a Cartesian manner relative to orthogonal anatomical reference planes as shown in FIG. 2. Angulation: Varus-Valgus, Flexion-Extension and Internal-External Rotation. Linear Position: Inferior-Superior, Anterior-Posterior and Medial-Lateral. To position the component on the bone, a number of datum features of the patients anatomy and their relative location as controlled by soft tissue structures at the knee may be utilized.

[0014] Two major schools of though exist as to the optimum method to provide consistent functional placement. The first is independent femoral anatomical placement. In this technique the femoral component is positioned on the femur by referencing datum features on the femur itself. The second is referenced to the tibial position. In this technique the position of the femoral component is controlled relative to the proximal cut of the tibia. The ligaments and other soft tissue structures at the knee joint will in this case affect the femoral components position. The positional referencing, according to different methodologies, is performed surgically prior to placing the femoral component.

[0015] A third technique is varus-valgus and flexion-extension. Angulation of the component in planes is usually performed simultaneously. The reference datum is either the femoral shaft or the line joining the center of the knee and the hip joints. Two major techniques for accomplishing this are currently used. First is intramedullary alignment. A rod is introduced through the center of the knee into the intramedullary space and passed up the inside of the femur to the internal isthmus, establishing an instrument axis within the femoral shaft (medullary canal of the femur). This technique has been found to be very reliable. The second is extramedullary alignment. An external guide rod is aligned with the anterior cortex of the femur, or from the center of the knee to the femoral head.

[0016] Current techniques generally require the sequential use of alignment and cutting guides. In most current systems multiple cutting guides are needed to fully prepare the distal femur for the implant. Because these sequential operations require the assembly and disassembly of instrument configurations and the use of intermediate data cut onto the bone, there are penalties in terms of time of surgery and accuracy.

[0017] U.S. Pat. No. 5,454,816 discloses an orthopedic instrument for guiding a saw blade for shaping the distal end of a human femur to receive an endoprosthetic femoral component. The instrument includes a base component provided with a guide for guiding cutting elements for shaping all of the necessary surfaces to receive the femoral component to be fitted once said base component is fitted to the bone. Also included are alignment elements for aligning the base component on the bone and elements for attaching the base component to the bone after alignment.

[0018] All of the prior art cutting guides have certain drawbacks. These include the inability to provide accurate cuts on a variety of different size femurs, inability to accurately align with one or more of the femoral axes, difficulty in fixation of the guide to the femur, inability to make adjustments in positioning after alignment tools are removed, impingement of soft tissue when securing the cutting guide, etc.

SUMMARY OF THE INVENTION

[0019] It is therefore an object of the invention to provide methods and tools for performing femoral resection.

[0020] It is also an object of the invention to provide tools for performing femoral resection which maintain proper alignment while multiple resection cuts are made.

[0021] It is another object of the invention to provide methods for performing femoral resection in which a minimum number of tools are used.

[0022] It is still another object of the invention to provide methods and tools which enhance the accuracy of femoral resection.

[0023] It is also an object of the invention to provide methods and tools for performing femoral resection on a variety of different size femurs.

[0024] It is another object of the invention to provide methods and tools for performing femoral resection which allow for intraoperative adjustment of the cutting guide position.

[0025] It is still another object of the invention to provide tools for performing femoral resection which are easy to attach to the femur with minimal soft tissue impingement.

[0026] In accord with these objects which will be discussed in detail below, the invention contemplates a tool set, including a plurality of different size cutting blocks (also referred to herein as “cutting guides”); and methods for resecting the distal femur prior to implanting a prosthetic femoral component.

[0027] The cutting guides of the present invention, according to preferred embodiments thereof, each include (a) a block having a plurality of guiding surfaces, the plurality of guiding surfaces including (a1) an anterior cutting guide surface for resecting the anterior cortex of the femur; (a2) a posterior cutting guide surface for resecting the posterior condyles; (a3) an anterior chamfer cutting guide surface; (a4) a posterior chamfer cutting guide surface; (a5) a distal cutting guide surface for resecting the distal end of the femur; and (b) means for securing said block to the distal femur.

[0028] The femoral resection tools of the present invention include a posterior condyle alignment guide, an IM rod with an adjustable valgus bushing assembly, zero, three, and five degree, left and right external rotation plates, an anterior sizing boom having a stylus and a pair of medial/lateral drill guides, a plurality of self-tapping screws, 0 mm, 2 mm and 4 mm proximal positioning fixtures with optional 2 mm anterior and posterior positioning fixtures, and a plurality of different size cutting guide blocks (the aforementioned “cutting guides”), each adapted to fit over the proximal positioning fixtures.

[0029] As indicated hereinabove, the cutting guide blocks contemplated by the preferred embodiment of the invention, provide three point cutting blade contact for guiding the anterior resection, posterior resection, posterior chamfer, anterior chamfer, and distal resection.

[0030] According to the methods of the invention, the valgus bushing is attached to the appropriate external rotation guide plate and both are attached to the posterior condyle alignment guide. An access hole is drilled into the IM canal. The IM rod is inserted through the valgus bushing and in the IM canal so that the assembly rests against the distal and posterior surfaces of the femur.

[0031] The assembly is locked securely into position and the anterior sizing boom is attached to the assembly. The stylus of the sizing boom is moved into position over the anterior femur and a size is indicated by indicia on a vertical post of the sizing boom.

[0032] The medial/lateral drill guides are moved against the medial and lateral sides of the femur and one or two fixation pins (self-tapping screws), depending on desired stability, are inserted through the holes in each drill guide. The drill guides, sizing boom, and alignment assembly are all removed leaving only the four fixation pins.

[0033] A pair of proximal positioning fixtures are selected and slid onto the fixation pins.

[0034] According to an alternate embodiment of the invention a pair of modular positioning fixtures can be detachably attached to the extension arms ahead of time to form an integrated drill guide assembly. According to the alternate embodiment of the invention, the need to select and slide a pair of positioning fixtures onto the fixation pins would be eliminated.

[0035] An appropriately sized cutting block is selected, based on the size indicated by the sizing boom, and is slid onto the proximal positioning fixtures. Additional fixation pins may then used to secure the position of the cutting block.

[0036] With the cutting block in place, five resections may be performed preferably in the following order: anterior resection, posterior resection, posterior chamfer, anterior chamfer, and distal resection. The rational behind this sequence is to allow the surgeon the ability to change the size and/or position of the femur immediately following the resection of the anterior femur.

[0037] The methods and tools of the invention provide for a wide range of alignment and sizing of the cutting guides described herein.

[0038] The cutting guides contemplated by the invention provide for very accurate cuts. The proximal positioning fixtures allow for 0 mm, 2 mm, or 4 mm distal offset and further, according to a presently preferred embodiment, also optionally permits +/−2 mm anterior/posterior offset to correct any mistakes made in the initial sizing of the femur. The cutting blocks contemplated by the invention also allow for medial-lateral positioning. All of these positioning steps can be carried out between cuts thereby allowing intraoperative adjustment of the position of a cutting block.

[0039] The invention provides all of the advantages of anterior referencing without the disadvantage of flexion gap anterior-posterior sizing mismatch.

[0040] Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041]FIG. 1 is a sectional view of a prior art femoral component;

[0042]FIG. 2 is a diagram showing the various reference directions for a knee;

[0043]FIG. 3 is a perspective view of the IM rod, valgus bushing, external rotation guide, and posterior alignment guide attached to a distal femur;

[0044]FIG. 4 is a view similar to FIG. 3, showing the anterior sizing boom and detachable drill guides attached to the assembly;

[0045]FIG. 5 is a view similar to FIG. 4, showing the fixation pins installed and one of the detachable drill guides removed;

[0046]FIG. 6 is a view similar to FIG. 5, showing the proximal positioning fixtures installed on the fixation pins;

[0047]FIG. 7 is a view similar to FIG. 6, showing a cutting block installed over the positioning fixtures;

[0048]FIG. 8 is a view similar to FIG. 7, illustrating the anterior resection of the femur;

[0049]FIG. 9 is a view similar to FIG. 7, illustrating the posterior resection of the femur;

[0050]FIG. 10 is a view similar to FIG. 7, illustrating the posterior chamfer cut;

[0051]FIG. 11 is a view similar to FIG. 7, illustrating the anterior chamfer cut; and

[0052]FIG. 12 is a view similar to FIG. 7, illustrating the distal resection of the femur.

DETAILED DESCRIPTION

[0053] Turning now to FIGS. 3-12, the methods and tools of the invention will be described in detail with reference to the order in which the tools are used in performing the methods of the invention.

[0054] As shown in FIG. 3, after the IM canal of the femur has been drilled, the valgus bushing 10 is attached to the appropriate external rotation guide plate 12 and both are attached to the posterior condyle alignment guide 14. The IM rod 16 is inserted through the valgus bushing 10 and in the IM canal so that the assembly rests against the distal and posterior surfaces of the femur. The assembly is locked securely into position with the locking knob 18.

[0055] According to one embodiment of the invention, the valgus bushing 10 allows the IM rod to pivot up to 9 degrees left or right and indicia boa on the bushing indicate the angle of the pivot.

[0056] Further, according to a preferred embodiment of the invention, several different external rotation guides are provided, namely, 3 degrees left, 3 degrees right, 5 degrees left, five degrees right, and 0 degrees (neutral) rotation. Each of the rotation guides is provided with a pair of wings 12 a, 12 b for visual reference to the traansepic ondylar axis; and a pair of vertical bores 12 c, 12 d. The posterior alignment guide 14 has a vertical portion 14 a which rests against the distal end of the femur, two vertical arms 14 b, 14 c which are spaced apart from the vertical portion 14 a and which are pressed against by the rotation guide 12 and a pair of horizontal feet 14 d, 14 e which rest against the posterior condyles of the femur.

[0057] Turning now to FIGS. 4 and 5. After the assembly is attached as described above, the anterior sizing boom 20 is attached to the assembly. The sizing boom has a pair of spaced apart vertical posts 20 a, 20 b which engage the bores 12 c, 12 d in the rotation guide. When so engaged, the sizing guide 20 rests on top of the alignment guide 14. The sizing boom 20 is also provided with a vertically movable stylus 20 c and sizing indicia 20 d which indicate the relative position of the stylus 20 c. A pair of drill guides 22 a, 22 b are removably attachable to the top of the boom 20.

[0058] After the boom 20 is attached to the rotation guide 12, the stylus 20 c of the sizing boom is moved into position over the anterior femur as illustrated in FIG. 4. The practitioner can locate the stylus on a region at the medial base of the most prominent aspect of the anterior lateral cortex. A size is indicated by indicia 20 d. This size can be used to select the appropriate cutting block as described below with reference to FIGS. 7 et seq.

[0059] The medial/lateral drill guides 22 a, 22 b can now be moved against the medial and lateral sides of the femur and locked in place. Fixation pins 24 (self-tapping screws as shown in the illustration), can now be inserted through the holes in each drill guide and be drilled into the sides of the femur.

[0060] The fixtures (positional fixtures) are detached from the extension arms; and the sizing boom, extension arms and alignment guide assembly may now all be removed leaving only the four fixation pins (and two positional fixtures in one embodiment of the invention). Preferably, the drill guides, extension arms and fixtures are removed one at a time to avoid strain on the fixation pins.

[0061] It should be recalled that according to an alternate embodiment of the invention a pair of modular positioning fixtures (“diodes”) are detachably attached to the extension arms ahead of time to form an integrated drill guide assembly. According to this alternate embodiment of the invention, the need to select and initially slide a pair of positioning fixtures onto the fixation pins would be eliminated.

[0062] Referring now to FIG. 6, after the fixation pins are installed and the rest of the instrumentation alignment apparatus. etc. is removed, the practitioner may select another pair of positioning fixtures that best suits the desired (appropriate) positional alignment of the femoral component. Each positioning fixture has two bores 26 a, 26 b. The bores are preferably spaced apart from each other by the same distance as the bores in the drill guide so that the fixtures 26 fit over the fixation pins 24 as shown in FIG. 6. They are easily inserted and removed by the practitioner.

[0063] According to one embodiment of the invention, different positioning fixtures are provided wherein the location of the bores 26 a, 26 b relative to the outer surface of the positioning fixture varies. Different modular positioning fixtures as integrated parts of a drill guide assembly (i.e., modular positioning fixtures attached to the extension arms of a drill guide, for example via a quick release mechanism) are, as indicated hereinbefore, contemplated by an alternative embodiment of the invention.

[0064] Further, according to one embodiment of the invention, the difference in location is only proximal-distal relative to the outer surface. E.g., 0 mm, 2 mm and 4 mm positioning fixtures are provided which will vary the proximal-distal location of the cutting block when it is placed over the fixtures as described below with reference to FIG. 7. The 0 mm fixture will provide a 8 mm initial resection. The 2 mm fixture will provide a 10 mm resection; and the 4 mm fixture will provide a 12 mm resection.

[0065] According to another embodiment of the invention, +/−2 mm positioning fixtures are provided which will vary the anterior-posterior location of the cutting block when it is placed over the fixtures. According to a preferred aspect of the invention, the positioning fixtures can be interchanged intraoperatively to make adjustments to the resected planes after the initial resection(s).

[0066] Turning now to FIGS. 7-12, after a pair of proximal positioning fixtures are selected and slid onto the fixation pins (referring to this one embodiment of the invention for the sake of illustration only), an appropriately sized cutting block 30 may be selected, based on the size indicated by the sizing boom. The cutting block 30 includes a central block member 32 having two chamfer cut slots 34, 36, an upper guiding surface 38, a lower guiding surface 40, a vertical guiding surface 41, and two end plates 42, 44.

[0067] Six guiding rods 46, 48, 50, 52, 54, 56 extend between the end plates 42, 44. Each end plate has a slot 42 a, 44 a for receiving a respective positioning fixture and a plurality of bores 42 b, 42 c, 44 b, 44 c for receiving fixation pins.

[0068] After the cutting block 30 is slid onto the proximal positioning fixtures 24, its medial-lateral location is adjusted by visual inspection. Note that osteophyte removal and patella resection may be required in obese patients in which femoral exposure is limited. Additional fixation pins 60 (self-tapping screws) may be used next to secure the position of the cutting block 30. As mentioned above, the cutting block is provided with four bores for fixation pins.

[0069] According to the preferred method of the invention, using one screw is acceptable for each side, e.g. lateral posterior and medial anterior. This minimizes soft tissue (patella tendon) interference and allows the intraoperative repositioning of the cutting block using the other two bores without drilling screws close to the previous holes. With the cutting block in place, five resections may be performed, preferably in the following order: anterior resection, posterior resection, posterior chamfer, anterior chamfer, and distal resection.

[0070]FIG. 8 illustrates the anterior resection cut wherein the cutting blade 70 is guided by the top surface 38 and the two bars 50, 52 of the cutting block 30. Thus, a three point cutting guide is provided for this cut.

[0071]FIG. 9 illustrates the posterior resection cut wherein the cutting blade 70 is guided by the bottom surface 40 and the two bars 54, 56 of the cutting block 30. Thus, a three point cutting guide is provided for this cut.

[0072]FIG. 10 illustrates the posterior chamfer resection wherein the cutting blade 70 is guided by the two surfaces defining slot 34 and bar 52 of the cutting block 30. Thus, a three point cutting guide is provided for this cut.

[0073]FIG. 11 illustrates the anterior chamfer resection wherein the cutting blade 70 is guided by the two surfaces defining slot 36 and bar 54 of the cutting block 30. Thus, a three point cutting guide is provided for this cut.

[0074]FIG. 12 illustrates the distal resection cut wherein the cutting blade 70 is guided by the vertical surface 41 and the two bars 46, 48 of the cutting block 30. Thus, a three point cutting guide is provided for this cut.

[0075] After all five resection cuts are completed, the cutting block may be removed and the resected surfaces can be examined. Additional resections may be performed using different positioning fixtures to fine tune the operation. When all resections are complete, the cutting block, positioning fixtures, and fixation screws are removed.

[0076] The methods and tools of the invention provide for a wide range of alignment and sizing of the cutting guide. The cutting guides contemplated by the invention provide for very accurate cuts since metal-to-metal surfaces are eliminated thus allowing the resultant slot to be tighter toleranced. The proximal positioning fixtures allow for 0 mm, 2 mm, or 4 mm distal offset and further, according to a presently preferred embodiment, also permit +/−2 mm anterior/posterior offset to correct any mistakes made in the initial sizing of the femur. The cutting blocks contemplated by the invention also allow for medial-lateral positioning. All of these positioning steps can be carried out between cuts thereby allowing intraoperative adjustment of the position of the cutting block. The invention provides all of the advantages of anterior referencing without the disadvantage of flexion gap anterior-posterior sizing mismatch.

[0077] There have been described and illustrated herein methods and tools for resection of the distal femur. While particular embodiments of the invention have been described, it is not intended that the invention be limited thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise. For example, those skilled in the art will readily appreciate that it is not necessary to be constrained by the preferred embodiment choices of offsets, correction factors, etc., these being application design choices for the tools and cutting guides per se.

[0078] It will therefore be appreciated by those skilled in the art that yet other modifications could be made to the provided invention without deviating from its spirit and scope as so claimed. 

What is claimed is:
 1. A cutting guide for resecting the distal femur prior to implanting a prosthetic component, said guide comprising: (a) a block having a plurality of guiding surfaces, said plurality of guiding surfaces including: (a1) an anterior cutting guide surface for resecting the anterior cortex of the femur; (a2) a posterior cutting guide surface for resecting the posterior condyles; (a3) an anterior chamfer cutting guide surface; (a4) a posterior chamfer cutting guide surface; and (a5) a distal cutting guide surface for resecting the distal end of the femur; and (b) means for securing said block to the distal femur.
 2. A cutting guide according to claim 1 further comprising means for locating the proximal-distal location of the cutting guide relative to the distal end of the femur.
 3. A cutting guide according to claim 1 wherein said anterior cutting guide surface includes a planar surface and two rods.
 4. A cutting guide according to claim 3 wherein said posterior cutting guide surface includes a planar surface and two rods.
 5. A cutting guide according to claim 4 wherein said posterior chamfer cutting guide surface includes two planar surfaces and a rod.
 6. A cutting guide according to claim 5 wherein said anterior chamfer cutting guide surface includes two planar surfaces and a rod.
 7. A cutting guide according to claim 6 wherein said distal cutting guide surface includes a planar surface and two rods.
 8. A cutting guide according to claim 1 wherein said block defines a pair of pin receiving holes and said means for securing said block includes a pair of pins dimensioned to fit through said holes.
 9. A cutting guide according to claim 1 further comprising means for locating the anterior-posterior location of the cutting guide relative to the distal end of the femur.
 10. A set of tools for resecting the distal end of the distal femur prior to implanting a prosthetic component, said set of tools comprising: (a) locating means for locating a medial location and a lateral location on the femur; (b) a pair of positioning fixtures adapted to be affixed to said medial location and said lateral location; (c) a cutting block having a plurality of guiding surfaces and means for engaging with said pair of positioning fixtures; and (d) means for securing said block to the distal femur.
 11. A set of tools according to claim 10, wherein said locating means includes an anterior sizing boom and an IM rod, said anterior sizing boom having a pair of drill guides adapted to overlie said medial location and said lateral location.
 12. A set of tools according to claim 11, wherein said locating means includes a posterior alignment guide.
 13. A set of tools according to claim 12, wherein said locating means includes a valgus bushing assembly and an external rotation fixture.
 14. A set of tools according to claim 10, wherein said pair of positioning fixtures includes a set of pairs of positioning fixtures, each pair interacting with said cutting block to locate said cutting block a different proximal-distal distance from the distal end of the femur.
 15. A set of tools according to claim 10, wherein said pair of positioning fixtures includes a set of pairs of positioning fixtures, each pair interacting with said cutting block to locate said cutting block a different anterior-posterior distance from the distal end of the femur.
 16. A set of tools according to claim 14, wherein said pairs of positioning fixtures locate said cutting block a distance from the distal end of the femur to resect an amount selected from the group consisting of 8 mm, 10 mm, 12 mm and 14 mm.
 17. A set of tools according to claim 15, wherein said pairs of positioning fixtures locate said cutting block +/−2 mm anteriorally-posteriorally.
 18. A set of tools according to claim 13, wherein said external rotation fixture includes a set of external rotation fixtures having rotation values selected from the group consisting of 0 degrees, 3 degrees left, 3 degrees right, 5 degrees left, and 5 degrees right.
 19. A set of tools according to claim 10, wherein said plurality of guiding surfaces includes: (a1) an anterior cutting guide surface for resecting the anterior cortex of the femur; (a2) a posterior cutting guide surface for resecting the posterior condyles; (a3) an anterior chamfer cutting guide surface; (a4) a posterior chamfer cutting guide surface; and (a5) a distal cutting guide surface for resecting the distal end of the femur.
 20. A set of tools according to claim 19 wherein said anterior cutting guide surface includes a planar surface and two rods.
 21. A set of tools according to claim 20 wherein said posterior cutting guide surface includes a planar surface and two rods.
 22. A set of tools according to claim 21 wherein said posterior chamfer cutting guide surface includes two planar surfaces and a rod.
 23. A set of tools according to claim 22 wherein said anterior chamfer cutting guide surface includes two planar surfaces and a rod.
 24. A set of tools according to claim 23 wherein said distal cutting guide surface includes a planar surface and two rods.
 25. A set of tools according to claim 24 wherein said block defines a pair of pin receiving holes and said means for securing said block includes a pair of pins dimensioned to fit through said holes.
 26. A method for resecting the distal femur prior to implanting a prosthetic component, said method comprising the steps of: (a) securing a cutting block to the distal end of the femur, the block having a plurality of guiding surfaces, the plurality of guiding surfaces including: (a1) an anterior cutting guide surface for resecting the anterior cortex of the femur; (a2) a posterior cutting guide surface for resecting the posterior condyles; (a3) an anterior chamfer cutting guide surface; (a4) a posterior chamfer cutting guide surface; and (a5) a distal cutting guide surface for resecting the distal end of the femur; (b) resecting the anterior cortex of the femur using a saw placed against the anterior cutting guide surface; (c) resecting the posterior condyles using a saw placed against the posterior cutting guide surface; (d) resecting an anterior chamfer using a saw placed against the anterior chamfer cutting guide surface; (e) resecting a posterior chamfer using a saw placed against the posterior chamfer cutting guide surface; and (f) resecting the distal end of the femur using a saw placed against the distal cutting guide surface.
 27. A method according to claim 26 further comprising the step of locating the proximal-distal location of the cutting guide relative to the distal end of the femur.
 28. A method according to claim 26 wherein the anterior cutting guide surface includes a planar surface and two rods and said step of resecting the anterior cortex includes placing a saw between the planar surface and the two rods.
 29. A method according to claim 28 wherein posterior cutting guide surface includes a planar surface and two rods and said step of resecting the posterior condyles includes placing a saw between the planar surface and the two rods.
 30. A method according to claim 29 wherein the posterior chamfer cutting guide surface includes two planar surfaces and a rod and said step of resecting the posterior chamfer includes placing a saw between the two planar surfaces and against the rod.
 31. A method according to claim 30 wherein the anterior chamfer cutting guide surface includes two planar surfaces and a rod and said step of resecting the anterior chamfer includes placing a saw between the two planar surfaces and against the rod.
 32. A method according to claim 31 wherein the distal cutting guide surface includes a planar surface and two rods and said step of resenting the distal surface of the femur includes placing a saw between the planar surface and the two rods.
 33. A method according to claim 26 wherein the block defines a pair of pin receiving holes and said step of securing the block includes inserting a pair of pins dimensioned to fit through said holes into the femur.
 34. A method according to claim 26 further comprising the step of locating the anterior-posterior location of the cutting guide relative to the distal end of the femur.
 35. A method for resecting the distal end of the distal femur prior to implanting a prosthetic component, said method comprising the steps of: (a) locating a medial location and a lateral location on the femur; (b) affixing positioning fixtures to the medial location and the lateral location; (c) placing a cutting block having a plurality of guiding surfaces on the pair of positioning fixtures, and (d) securing the block to the distal femur.
 36. A method according to claim 35, wherein said step of locating includes attaching an anterior sizing boom and an IM rod to the femur and attaching a pair of drill guides adapted to overlie the medial location and the lateral location to the sizing boom.
 37. A method according to claim 36, wherein said step of locating means includes coupling a posterior alignment guide to the IM rod.
 38. A method according to claim 37, wherein said step of locating includes coupling a valgus bushing assembly and an external rotation fixture to the IM rod.
 39. A method according to claim 35, wherein said step of affixing positioning fixtures includes choosing a pair of positioning fixtures from a group of pairs wherein each pair interacts with the cutting block to locate the cutting block a different proximal-distal distance from the distal end of the femur.
 40. A method according to claim 35, wherein said step of affixing positioning fixtures includes choosing a pair of positioning fixtures from a group of pairs wherein each pair interacts with the cutting block to locate the cutting block a different anterior-posterior distance from the distal end of the femur.
 41. A method according to claim 39, wherein the pairs of positioning fixtures locate the cutting block a distance from the distal end of the femur to resect an amount selected from the group consisting of 8 mm, 10 mm, 12 mm and 14 mm.
 42. A method according to claim 15, wherein the pairs of positioning fixtures locate the cutting block +/−2 mm anteriorally-posteriorally.
 43. A method according to claim 38, wherein the external rotation fixture includes a set of external rotation fixtures having rotation values selected from the group consisting of 0 degrees, 3 degrees left, 3 degrees right, 5 degrees left, and 5 degrees right.
 44. A method according to claim 35, wherein the plurality of guiding surfaces includes: (a1) an anterior cutting guide surface for resecting the anterior cortex of the femur; (a2) a posterior cutting guide surface for resecting the posterior condyles; (a3) an anterior chamfer cutting guide surface; (a4) a posterior chamfer cutting guide surface; (a5) a distal cutting guide surface for resecting the distal end of the femur; and said method further comprising the steps of: (e) resecting the anterior cortex of the femur using a saw placed against the anterior cutting guide surface; (f) resecting the posterior condyles using a saw placed against the posterior cutting guide surface; (g) resecting an anterior chamfer using a saw placed against the anterior chamfer cutting guide surface; (e) resecting a posterior chamfer using a saw placed against the posterior chamfer cutting guide surface; and (h) resecting the distal end of the femur using a saw placed against the distal cutting guide surface.
 45. A method according to claim 44 wherein the anterior cutting guide surface includes a planar surface and two rods and said step of resecting the anterior cortex includes placing a saw between the planar surface and the two rods.
 46. A method according to claim 45 wherein the posterior cutting guide surface includes a planar surface and two rods and said step of resecting the posterior condyles includes placing a saw between the planar surface and the two rods.
 47. A method according to claim 46 wherein the posterior chamfer cutting guide surface includes two planar surfaces and a rod and said step of resecting the posterior chamfer includes placing a saw between the two planar surfaces and against the rod.
 48. A method according to claim 47 wherein the anterior chamfer cutting guide surface includes two planar surfaces and a rod and said step of resecting the anterior chamfer includes placing a saw between the two planar surfaces and against the rod.
 49. A method according to claim 48 wherein the distal cutting guide surface includes a planar surface and two rods and said step of resecting the distal femur includes placing a saw between the planar surface and the two rods.
 50. A method according to claim 49 wherein the block defines a pair of pin receiving holes and said step for securing said block includes inserting a pair of pins dimensioned to fit through said holes into the femur.
 51. Apparatus according to claim 11 wherein said positioning fixtures are integrated with said drill guide.
 52. Apparatus according to claim 11 wherein said positioning fixtures are modular.
 53. Apparatus according to claim 11 wherein each of said positioning fixtures are detachably attached to a drill guide extension arm to form an integrated drill guide assembly.
 54. A method according to claim 36 wherein said positioning fixtures are integrated with said drill guide.
 55. A method according to claim 36 wherein said positioning fixtures are modular.
 56. A method according to claim 36 wherein each of said positioning fixtures are detachably attached to a drill guide extension arm to form an integrated drill guide assembly. 